1. Field of the Invention
The subject invention relates to surfboard structures and, more specifically, to surfboards with adjustable fins and to adjustable fin holders.
2. Description of the Prior Art
In order to provide for improved surfboard handling and surfer performance, it is important that the fin of a surfboard be longitudinally adjustable.
In this respect, one prior-art proposal provides a keel or fin holder attached to the surfboard with a plurality of apertures. The keel or fin, in turn, is longitudinally slidable in the keel or fin holder and has a number of corresponding openings. Retractable fastening devices extend through corresponding apertures and holes to hold the adjusted fin in position (see U.S. Pat. No. 3,308,493).
In practice, it has been found that fin adjustment as small as some 3 millimeters can have a discernible effect on the precision control of the board by a skilled surfer. Such a fine control, however, is not feasible with the construction according to the above mentioned prior-art proposal, since the requisite multitude of holes for apertures in the fin base or holder would seriously weaken the structure, promoting accidental separation of the fin from the board.
In an effort to solve this problem, another prior-art proposal U.S. Pat. No. 3,564,632) has provided a channel member in the underside of the surfboard for receiving the base member of a fin. Releasable fasteners interconnect the channel member and the base member for creating frictional engagement of the base member with the channel member in an endeavor to provide secured, longitudinal positioning with infinite adjustment of the fin along the length of the channel member.
In practice, orientation in terms of an infinite adjustment leads to undesirable limitations. In particular, such insistence limits suitable fastening techniques to those relying on frictional engagement of the fin base member with the channel member. This, in turn, has necessitated the use of fastening devices which have proved awkward to handle and exposed to deterioration in a marine environment. This problem has persisted even after a replacement of one of the formerly two fastening devices by a transverse pin which rides in lateral slots in the channel member.